Need a Carburettor Spring

[alk]

I've been having some problems with my '84 CB700 stalling and running poorly lately. When I took the carbs off I noticed that I'm missing one of the carb springs. The springs I'm talking about are the ones that push the butterfly valves closed. The spring I'm missing is off the second carb from the right when sitting on the bike facing forward, either #2 or #3, the middle one that isn't connected to the throttle cables. Without this spring it's obvious that the two carbs on the right side have their butterfly valves opened more than the other two. I think this is what's causing my problems.

I checked the parts catalogue and the springs aren't sold seperately, only with the entire carb body. I don't think I could live with myself buying an entire new carb or set of carbs just to replace 1 little spring. I went to a motorcycle salvage yard (the bikeyard) and found a set of damaged carbs from another CB model hoping I could use its springs. It turns out those springs are too big. I'm considering going to a hardware store and trying to find a similar spring. The problem is I think it would be very difficult to bend the hooks in the specific orientation required. Does anyone know of an easier solution?

If anyone has this spring or an extra set of (cheap) broken/old/rusted carbs they could sell me I'd appreciate it.

[ariwhiteboy]

Try this site, they have most parts you could need.

http://www.hondaparts-direct.com/default.asp

[alk]

If they sell the spring I don't see it. Here are the two carb pages for my motorcycle:

http://www.hondaparts-direct.com/fiche_section_detail.asp?section=123990&category=MOTORCYCLES&make=HONDA&year=1984&fveh=2961

http://www.hondaparts-direct.com/fiche_section_detail.asp?section=123991&category=MOTORCYCLES&make=HONDA&year=1984&fveh=2961

You can see one of the springs I'm talking about if you look at that first link, on the carb labeled #8 if you look to the left of and slightly above the carb opening that goes to the engine. I need that spring for the carb labeled #9.

[gammer]

I have two spare sets of carbs for the Nighthawk S. I'd have to take them apart to get the spring, as they are still as 1 bank of carbs. If no one else here gives you a spring from carbs they already have apart, then let me know? and I'll give you one from one of mine.

[fishmeister]

$6 from Honda

[alk]

gammer:

That would be amazing! How much would you want for the spring? I see that you're in Canada. I'm in San francisco California, is there any hard-to-get-in-Canada specialty USA items I could send you to show my gratitude?

fishmeister:

Can you give me a part number or a link to where I can buy these springs? In the links I posed above it doesn't look like those springs are anywhere in the official parts catalogue. I called a Honda dealership and asked about the springs and was told that they are only sold along with the carb body.

I took pictures to hopefully make things clearer:

All carbs in order with missing spring highlighted:


Closeup of missing spring next to corresponding spring on other carb:

[fishmeister]

http://www.cyclepartswarehouse.com/fiche_section_detail.asp?section=123990&category=MOTORCYCLES&make=HONDA&year=1984&fveh=2961

#4? Two required?

[alk]

Those springs are different, there are only two of them and they are sandwiched between both pairs of outter and inner carbs. I'm not completely sure why they are necessary as the front and rear brackets prevent the carbs from moving at all.

[gammer]

I'm still not sure of what screw you are talking about? But then again I've never taken my carbs apart individually. I've only had them off as 1 bank.
I'll have to take them apart to see what you are referring to.

[alk]

Hopefully this will help:



When you open the butterfly valves, the metal disk in the main passageway, you push against these springs. These are what return the valves to the closed position when you roll off the throttle. The spring will have a little hook that connects it to the rotating piece with the synchronization adjustment screw on it.

[gammer]

Gotcha...In know exactly what you mean now. Thank you, that last pic helped allot.
Again, I do have this spring on a spare set of carbs. I will have to pull them apart to get at it. So if no one else offers it to you, then I will get you one of mine.

[gammer]

After looking at the pic closely...



...you will need more then just the spring. It looks like you need that bracket that the spring hooks into? The bracket with the screw on it (that is the screw you adjust when doing a carb sync)

[alk]

Thanks a lot, I'm looking everywhere for an extra spring or cheap set of carbs. This weekend I'm going to try driving out to another motorcycle junkyard, maybe I'll get lucky.

As for the lack of pieces in the picture, I have them all, I just took them off to try using some springs I pulled off a set of junkyard carbs from a different model Nighthawk. They didn't fit.

[alk]

Someone recommended I check out McMaster-Carr, they really have everything!

I could try ordering one of these:

http://www.mcmaster.com/#torsion-springs/=7iaysg

I can find out most of the information by measuring the other coils, what I would needs someones help with would be the number of coils the spring has and someones best guess at the torque. Can someone think of a way to measure the torque on one of the other springs. Something like hanging a weight from one end and adjusting it until I find equilibrium. Would torque be a simple function number of coils assuming both springs have the same stiffness?